Variable compression ratio scheduling at idle speed conditions

Details Variable compression ratio scheduling at idle speed conditions Variable compression ratio scheduling at idle speed conditions

2007-09-11

2007-09-11

Cronin, Stephen K. (Department: 3747)

Internal-combustion engines

Adjustable combustion chamber

Piston in head adjusted

Reexamination Certificate

active

11291382

ABSTRACT:
A method for selecting compression ratio of a variable compression ratio internal combustion engine when such engine is operating under an idle condition is disclosed. The compression ratio is selected to avoid engine knock, an undesirable phenomenon which is more likely at higher temperatures, higher compression ratios, lower engine speeds, and higher engine torques. The selected compression ratio is based on one or more of engine torque required to drive engine accessories, engine coolant temperature, engine air temperature, and transmission status (neutral idle or drive idle). A normalized airflow parameter is computed or found in a lookup table based on engine coolant temperature and engine air temperature. When actual normalized airflow (that which provides necessary engine torque to drive engine accessories and overcome engine friction) exceeds normalized airflow parameter exceeds, a higher compression ratio is selected.

REFERENCES:
patent: 4724810 (1988-02-01), Poirier et al.
patent: 5400755 (1995-03-01), Maebashi
patent: 6553949 (2003-04-01), Kolmanovsky et al.
patent: 6970781 (2005-11-01), Chen et al.
patent: 7028647 (2006-04-01), Styron

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